Unraveling the jet-lag asymmetry

Jet lag, the sluggishness we feel after landing in a new time zone, has a directional bias: Studies suggest it takes longer to recover from eastward travel than from westward travel. A new model developed by Michelle Girvan, Edward Ott, Thomas Antonsen, and colleagues at the University of Maryland, College Park, may explain why. The team used tools of nonlinear dynamics to model a region of the brain known as the suprachiasmatic nucleus (SCN), a network of roughly 20 000 time-keeping neurons devoted to maintaining the body’s circadian rhythm. Jet lag happens when those neurons fall out of sync with the local cycle of night and day. Modeling the dynamics of the SCN, however, is a tall order. Although the neurons all take cues from the same source—the retina—they don’t all respond in the same way. Nor do they share the same natural oscillation periods; absent visual cues, the periods...